Basic Electrical And Instrumentation Engineering

416 Pages·2018·4.156 MB·English

by  S. Salivahanan, R. Rengaraj, G.R. Venkatakrishnan

BASIC ELECTRICAL AND
INSTRUMENTATION ENGINEERING
A A
BOUT THE UTHORS
S. Salivahanan is the Principal of SSN College of Engineering, Chennai. He obtained
his B.E. degree in Electronics and Communication Engineering from PSG College of
Technology, Coimbatore, M.E. degree in Communication Systems from NIT, Trichy
and Ph.D. in the area of Microwave Integrated Circuits from Madurai Kamaraj
University. He has four decades of teaching, research, administration and industrial
experience both in India and abroad. He has taught at NIT, Trichy, A.C. College of
Engineering and Technology, Karaikudi, RV College of Engineering, Bangalore, and
Mepco Schlenk Engineering College, Sivakasi. He has industrial experience as Sci-
entist/Engineer at Space Applications Centre, ISRO, Ahmedabad, Telecommunication
Engineer at State Organization of Electricity, Iraq and Electronics Engineer at Electric Dar Establishment,
Kingdom of Saudi Arabia.
He is the author of 40 popular books which include all-time bestsellers such as Basic Electrical and
Electronics Engineering, Electronic Devices and Circuits, Linear Integrated Circuits, and Digital Signal
Processing, all published by McGraw Hill Education. He has also authored the books on Digital Circuits
and Design, Electromagnetic Field Theory, Circuit Theory, Network Analysis and Synthesis and Control
Systems Engineering. He has published several papers at national and international levels.
Professor Salivahanan is the recipient of Bharatiya Vidya Bhavan National Award for Best Engineering
College Principal for 2011 from ISTE, and IEEE Outstanding Branch Counsellor and Advisor Award in
the Asia-Pacific region for 1996–97. He was the Chairman of IEEE Madras Section for two years 2008 and
2009 and Syndicate Member of Anna University.
He is a Senior Member of IEEE, Fellow of IETE, Fellow of Institution of Engineers (India), Life Mem-
ber of ISTE and Life Member of Society for EMC Engineers. He is also a member of IEEE societies in
Microwave Theory and Techniques, Communications, Signal Processing, and Aerospace and Electronics.
R. Rengaraj is Associate Professor in the Department of Electrical and Electronics
Engineering, SSN College of Engineering, Chennai. He obtained his B.E. degree in
Electrical and Electronics Engineering from Manonmaniam Sundaranar University,
Tirunelveli, M.E. degree in Power Systems Engineering and Ph.D. in the area of Com-
bined Heat and Power, both from Anna University, Chennai. He has authored a book
onControl Systems Engineering. He has more than 13 years of teaching and research
experience. He has published several research publications in refereed international
journals and in the proceedings of international conferences. He has received TATA
Rao Gold Medal from the Institution of Engineers (India) in 2011. He is a Life Member
of ISTE and a Member of IEEE.
G.R. Venkatakrishnan is Assistant Professor in the Department of Electrical and
Electronics Engineering, SSN College of Engineering, Chennai. He obtained his B.E.
degree in Electrical and Electronics Engineering and M.E. degree in Control Systems
from Anna University, Chennai. He has authored a book on Control Systems Engineer-
ing and has published many research papers in national and international journals and
conferences. He is a Life Member of ISTE and a Member of IEEE.
BASIC ELECTRICAL AND
INSTRUMENTATION ENGINEERING
S. Salivahanan
Principal
SSN College of Engineering
Chennai
R. Rengaraj
Associate Professor
Department of Electrical and Electronics Engineering
SSN College of Engineering
Chennai
G.R. Venkatakrishnan
Assistant Professor
Department of Electrical and Electronics Engineering
SSN College of Engineering
Chennai
McGraw Hill Education (India) Private Limited
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Basic Electrical and Instrumentation Engineering
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C
ONTENTS
Preface ix
1. AC Circuits and Power Systems 1
1.1 Introduction 1
1.2 Three-Phase Supply 1
1.3 Basics of a Three-Phase Power System 3
1.4 Generation of Three-Phase Voltages 5
1.5 Analysis of the Three-Phase System 6
1.6 Steps to Draw Phasor Diagram 17
1.7 Star–Delta Conversion 17
1.8 Power Measurment in a Three-Phase System 31
1.9 Introduction to Electric Power System 44
1.10 Introduction to Power System Protection 48
1.11 Circuit Breaker 49
1.12 Fuse 52
1.13 Protective Relays 55
1.14 Introduction to Tariff 57
1.15 Power Factor 63
1.16 Power Factor Improvement or Correction 65
Two-Mark Questions and Answers 68
Review Questions 71
2. Transformers 72
2.1 Introduction 72
2.2 Single-Phase Transformer 72
2.3 EMF Equation of the Transformer 78
2.4 Reasons for not Using DC Supply as a Source 79
2.5 Types of Transformers 79
2.6 Ideal Transformer 80
2.7 Accounting for Finite Permeability and Core Loss 80
2.8 Transformer on Load 82
vi Contents
2.9 Effect of Winding Resistances 89
2.10 Effect of Leakage Reactance 91
2.11 Winding Impedance 92
2.12 Transformer on Load with Winding Impedances 94
2.13 Circuit Model or Equivalent Circuit of Transformer 96
2.14 Per Unit System 100
2.15 Voltage Regulation 100
2.16 Name Plate Rating of a Transformer 104
2.17 Losses in a Transformer 107
2.18 Efficiency of the Transformer 108
2.19 All-Day Efficiency 112
2.20 Determination of Parameters of Circuit Model of Transformer 117
2.21 Auto-Transformer 125
2.22 Three-Phase Transformer 130
2.23 Voltage and Current Relationship for Different Connections 135
Two Mark Questions and Answers 137
Review Questions 141
3. DC Machines 145
3.1 Introduction 145
3.2 DC Generator 145
3.3 Armature Reaction 154
3.4 Commutation 156
3.5 Types of DC Generators 157
3.6 Electrical Equivalent Circuits, Current and Voltage Equations of DC Generators 158
3.7 Characteristics of DC Generators 164
3.8 Applications of DC Generators 171
3.9 DC Motor 171
3.10 Types of DC Motor 176
3.11 Characteristics of DC Motors 183
3.12 Speed Control of DC Motors 191
3.13 Losses in DC Machines 194
3.14 Power-Flow Diagram 196
3.15 Starting DC Motors 197
3.16 Applications of DC Motors 199
3.17 Universal Motor 200
Two Mark Questions and Answers 202
Review Questions 205
Contents vii
4. AC Machines 207
4.1 Introduction 207
4.2 Three-Phase Induction Motor 207
4.3 Slip of an Induction Motor 213
4.4 Effect of Slip on Rotor Parameters 214
4.5 Three-Phase Induction Motor vs Transformer 218
4.6 Torque Equation 221
4.7 Effect of Change in Rotor Resistance on Torque 227
4.8 Effect of Change in Rotor Reactance onTorque 227
4.9 Losses in Induction Motors 236
4.10 Power Flow in Induction Motor 236
4.11 Relation Between P,P and P 237
2 c m
4.12 Efficiency of an Induction Motor 240
4.13 Equivalent Circuit of an Induction Motor 240
4.14 Phasor Diagram of an Induction Motor 252
4.15 Starters 252
4.16 Speed Control of a Three-Phase Induction Motor 257
4.17 Single-Phase Induction Motor 260
4.18 Types of Single-Phase Induction Motors 262
4.19 Equivalent Circuit of a Single-Phase Induction Motor 266
4.20 Alternator or a Three-Phase AC Generator 268
4.21 EMF Equation of an Alternator 273
4.22 Parameters of Armature Winding 275
4.23 Synchronous Reactance and Synchronous Impedance 276
4.24 Equivalent Circuit of an Alternator 277
4.25 Voltage Equation of the Alternator 277
4.26 Phasor Diagram of the Loaded Alternator 277
4.27 Voltage Regulation of an Alternator 278
4.28 Synchronous Motor 284
4.29 Methods of Starting Synchronous Motors 286
4.30 Behaviour of a Synchronous Motor on Loading 288
4.31 Phasor Diagram 290
4.32 V and Inverted-V Curves 291
4.33 Expression for Back EMF or Induced EMF Per Phase in a Synchronous Motor 292
4.34 Power Flow in Synchronous Motor 293
4.35 Power Developed by a Synchronous Motor 294
4.36 Comparison Between Synchronous and Induction Motors 295
4.37 Stepper Motor 302
4.38 Brushless Direct Current (BLDC) Motor 307
Two Marks Questions and Answers 311
Review Questions 317
viii Contents
5. Measurement and Instrumentation 321
5.1 Introduction 321
5.2 Essential Requirements of Measuring Instruments 321
5.3 Elements of the Measuring Instruments 321
5.4 Types of Electrical and Electronic Measuring Instruments 324
5.5 Principles of Electrical Indicating Instruments 325
5.6 Types of Indicating Instruments 328
5.7 Moving-iron Instruments 328
5.8 Moving-coil Instruments 334
5.9 Electro Dynamometer Type 337
5.10 Electrothermic Instruments 342
5.11 Electrostatic Type Instrument 346
5.12 Induction Type Instruments 349
5.13 Rectifier Type Instruments 352
5.14 Ammeter 355
5.15 DC Voltmeter 357
5.16 Digital Voltmeter (DVM) 358
5.17 Ohmmeter 360
5.18 Digital Multimeter 363
5.19 Cathode Ray Oscilloscope 364
5.20 Static and Dynamic Characteristics of Instruments 372
5.21 Errors in Measurement 378
5.22 Introduction to Transducer 380
5.23 Classification of Transducers 380
5.24 Resistive Transducer 382
5.25 Inductive Transducer 389
5.26 Capacitive Transducers 392
5.27 Thermoelectric Transducer 394
5.28 Piezoelectric Transducer 396
5.29 Photoelectric Transducer 397
5.30 Hall Effect Transducers 398
5.31 Mechanical Tranducers 400
Two Mark Questions and Answers 402
Review Questions 404
P
REFACE
Basic Electrical and Instrumentation Engineering is designed specifically to cater to the needs of second
semester ECE students. The book has a perfect blend of focused content and complete coverage. Solved
university question papers, which are tagged with specific topics, will be extremely helpful to students from
the examination point of view. Simple, easy-to-understand and jargon-free text elucidates the fundamentals
of Electrical and Instrumentation Engineering. Several solved examples, schematic diagrams and adequate
questions further helps students to understand and apply the concepts.
SALIENT FEATURES
Comprehensive coverage as per the latest Basic Electrical and Instrumentation Engineering syllabus
Solutions of examination papers from 2010 to 2017 are present appropriately within thechapters
Solved university questions as solved examples incorporated appropriately within each chapter
Theory questions are tagged within each chapter
Rich exam-oriented pedagogy
Solved Numerical Examples within chapters: 96
Two-Mark Questions and Answers at the end of each chapter: 150
Unsolved Review Questions: 270
CHAPTER ORGANISATION
Chapter 1 deals with three phase power supply, three phase power measurement, transmission and
distribution of electrical energy, protection of power system, tariff and power factor improvement.
Chapter 2 is devoted to introduction of ideal transformer, circuit model of transformer and determina-
tion of parameters, efficiency and auto-transformers.
Chapter 3 describes the constructional features of various motors, methods of excitation and magneti-
sation characteristics, starting and speed control and universal motor.
Chapter 4 focuses on the principle of operation of three-phase induction motors, equivalent circuit,
single phase induction motors, types of starting and speed control methods, working principle of alterna-
tor, synchronous motors, stepper motors and brushless DC motors.
x Preface
Chapter 5 concentrates on the type of electrical and electronic instruments, principles of electrical
instruments, multimeters, oscilloscopes, transducers and their classifications and applications.
ACKNOWLEDGEMENTS
The authors sincerely thank the management of SSN College of Engineering, Chennai for the constant
encouragement, and for providing necessary facilities for completing this project.
The authors are highly appreciative of the editorial and production team of McGraw Hill Education (India)
for their initiation and support to bring out this edition in a short span of time.
The authors would like to take this opportunity to thank the reviewers especially the colleagues V. Thiyaga-
rajan, U. Shajith Ali, Alagudheeraj S. Malathy and D. Umarani from EEE department, and M. Karthikeyan
from Velammal Engineering College, Chennai for their useful comments and suggestions.
The authors would also like to thank Mr. G. Muralikrishnan, Panimalar Engineering College,Chennai, for
his valuable feedback.
Finally, they thank their family members Mrs. Kalavathy Salivahanan, S. Santhosh Kanna & S. Subadesh
Kanna, Mrs. Rajalakshmi Rengaraj, R. Harivarshan and Master R. Devprasath, and Mr. S. Rajan Babu,
Mrs. Sumathi Babu, Mrs. G. R. Hemalakshmi Prakash & Mrs. R. Jeya Jeyaprakash for their patience and
constant inspiration during the preparation of this book.
Any constructive criticism, suggestions and corrections for further improvement of the book will be most
appreciated.
S. Salivahanan
R. Rengaraj
G. R. Venkatakrishnan
Publisher’s Note:
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